In this work, measurements of p rho T (pressure-density-temperature) properties of trans-1-chloro-3,3,3-trifluoropropene (R 1233zd(E)) near the critical density were performed. This novel fluid has been proposed for organic Rankine cycle systems. However, there is no data near the critical density. In this work, 97 p rho T data points of R 1233zd(E) along 21 isochores for densities between 161 kg.m(-3) and 1202 kg.m(-3) were obtained in the temperature range from 328 to 443 K and at pressures up to 10 MPa. Almost all of the data were obtained near the critical density. The experimental uncertainties in the measurements of temperatures, pressures, densities below 200 kg.m(-3), and higher densities were estimated to be 0.028 K, 4 kPa, 0.5%, and 0.4%, respectively.